This invention relates to a method for manufacturing a speaker vibration member.
Speaker vibration members, which are one of the component elements of loudspeakers, are also known as diaphragms. In order to increase the range of their piston movement, they are required to have a high relative elastic coefficient E/.rho. (where E=elasticity and .rho.=density), and in order to provide a smooth response in the high frequency region, they are required to have suitable internal losses.
In the prior art, in order to increase E/.rho., carbon fiber was mixed into vibration members containing mainly paper pulp. In recent years, E/.rho. has been improved by mixing carbon fiber or mica into plastic materials. To increase internal losses, on the other hand, vibration members have been impregnated with organic paints.
In the above methods where carbon fiber is mixed with paper pulp, there are limitations to the amount of fiber so that in actual practice, it is not possible to expect a great increase in E/.rho.. In methods where carbon fiber or mica is mixed with plastic, the melt viscosity rises so that a restriction is imposed on the formation of the vibration member. Further, in methods where the vibration member is impregnated with organic paints, although internal losses do increase, E/.rho. falls. There have been other attempts to increase E/.rho. and obtain a vibration member with suitable internal losses, however it has so far been practically impossible to satisfy both of these requisites simultaneously in an economically viable process.